Flame-retardant polyester resin composition

ABSTRACT

A thermoplastic resin having such a sufficient heat shock resistance that it is unbroken by common temperature changes and also exhibiting an excellent flame resistance when applied to an insert molded article, which is obtained by blending a thermoplastic polyester resin (A) with 1-25% by weight to the total amount of the composition of an impact resistance giving agent (B), 1-50% by weight to the total amount of the composition of an inorganic filler (C), 1-25% by weight to the total amount of the composition of a flame retardant (D) and 0.1-10% by weight to the total amount of the composition of an aromatic polyvalent carboxylate (E).

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a polyester resin composition havingexcellent flame-retardance and heat shock property, and it also relatesto an insert molded article having excellent flame-retardance and heatshock property, obtained by an insert-molding of the polyester resincomposition with a metal or an inorganic solid.

BACKGROUND OF THE INVENTION

The insert molding method is a molding method in which a metal orinorganic solid (hereinafter, abbreviated as metals) is embedded in aresin for utilizing the property of the resin and the material propertyof the metals. It is applied in wide fields such as automobile parts andelectric and electronic parts, and presently one of general moldingmethods. However, since expansion and shrinkage coefficient (so-calledliner expansion coefficient) are extremely different between a resin andmetals, molded articles having thin resin portions, portions with largevariation in thickness or sharp corners composed of metals, suffer froma lot of troubles such as cracking just after molding and cracking bytemperature change in use. Particularly in the case of electric andelectronic parts, since high flame-retardance is also required,thermosetting resins such as phenol resins and epoxy resins are widelyused for an insert molding.

However, thermosetting resins have disadvantages such as lowerproductivity due to a long molding cycle and low recycling property, sothat substitution with thermoplastic resins is required eagerly.

SUMMARY OF THE INVENTION

The present inventors have intensively studied, in view of theabove-described problems, to obtain a thermoplastic resin for insertmolding, having excellent flame-retardance, not cracking by temperaturechange and having excellent heat shock property, and which can besuitably used for electric and electronic parts in particular. As aresult, it has been found that a composition, mainly comprising athermoplastic polyester resin and containing an impact resistance givingagent, inorganic filler, flame-retardant and aromatic ester compoundcompounded therein, is excellent in flame-retardance and heat shockproperty, and that an insert molded article prepared by using thiscomposition has sufficient flame-retardance as electric and electronicparts and simultaneously sufficient heat shock resistance causing nocrack by common temperature change, whereby completing the presentinvention.

That is, an object of the present invention is

a flame-retardant polyester resin composition, obtained by blending athermoplastic polyester resin (A) with

1 to 25% by weight, based on the total amount of the composition, of animpact resistance giving agent (B),

1 to 50% by weight, based on the total amount of the composition, of aninorganic filler (C),

1 to 25% by weight, based on the total amount of the composition, of aflame-retardant (D) and

0.1 to 10% by weight, based on the total amount of the composition, ofan aromatic polyvalent carboxylate (E),

and an insert molded article obtained by an insert-molding of theflame-retardant polyester resin composition with a metal or an inorganicsolid.

In other words, the composition comprises (A), 1-25% by weight of (B),1-50% by weight of (C), 1-25% by weight of (D) and 0.1-10% by weight of(E), which are all based on the total amount of the composition. Theamount of (A) may be 20-96.9% to 100% by weight of the composition.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described in detail below. First, thethermoplastic polyester resin (A), which is a base resin in the presentinvention, is a polyester obtained by, for example, polycondensation ofa dicarboxylic acid compound with a dihydroxy compound, polycondensationof an oxycarboxylic acid compound, and polycondensation of ternarycompounds thereof, and may be any of homopolyesters and copolyesters.Examples of the dicarboxylic acid compound constituting thethermoplastic polyester resin (A) herein used include known dicarboxylicacids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyl dicarboxylic acid, diphenyl etherdicarboxylic acid, diphenylethane dicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid and sebacic acid, and alkyl-, alkoxy- orhalogen-substituted compounds thereof. These dicarboxylic acid compoundscan also be used for polymerization in the form of ester-formablederivatives, for example, lower alcohol esters such as a dimethyl ester.

Then, examples of the dihydroxy compound constituting the thermoplasticpolyester resin (A) of the present invention include hydroxy compoundssuch as ethylene glycol, propylene glycol, butane diol, neopentylglycol, hydroquinone, resorcin, dihydroxyphenyl, naphthalene diol,dihydroxyphenyl ether, cyclohexane diol, 2,2-bis(4-hydroxyphenyl)propaneand diethoxylated bisphenol A, polyoxyalkylene glycol and alkyl-,alkoxy- or halogen-substituted compounds thereof, and one or more ofthem can be added. Examples of the oxycarboxylic acid compound includeoxycarboxylic acids such as oxybenzoic acid, oxynaphthoic acid anddiphenyleneoxycarboxylic acid, and alkyl-, alkoxy- orhalogen-substituted compounds thereof. Further, ester-formablederivatives of these compounds can also be used. In the presentinvention, one or more of these compounds are used. In addition to theabove-described compounds, polyesters having a branched or cross-linkedstructure obtained by using a small amount of a trifunctional monomer,such as, trimellitic acid, trimesic acid, pyromellitic acid,pentaerythritol and trimethylolpropane, may be used.

In the present invention, any of thermoplastic polyesters produced bypolycondensation using the above-described compounds as monomercomponents, can be used as the component (A) of the present invention,and they are used alone or in combination of two or more. Preferably, isused a polyalkylene terephthalate, further preferably a polybutyleneterephthalate and copolymers including such terephthalate as the maincomponent. In the present invention, thermoplastic polyesters may bemodified according to a known method such as cross-linking and graftpolymerization.

Representative examples of the impact resistance giving agent (B) usedin the present invention, thermoplastic elastomers and core-shellpolymers are cited. These thermoplastic elastomers are a generic name ofthe polymer substances which can be melt-mixed with thermoplasticpolyester resins because they are solids having rubber-like elasticityat normal temperature, but heating them decreases the viscosity thereof.

The kind of the thermoplastic elastomer is not particularly restricted,and olefin-, styrene-, polyester-, polyamide- and urethane-basedelastomers are listed, for example.

Preferable as the olefin-based elastomer are copolymers mainlycomprising ethylene and/or propylene, and specific examples thereofinclude, but are not limited to, an ethylene-propylene copolymer,ethylene-butene copolymer, ethylene-octene copolymer,ethylene-propylene-butene copolymer, ethylene-propylene-diene copolymer,ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer andethylene-glycidyl methacrylate copolymer. Among the olefin-basedelastomers, preferably used are graft copolymers obtained by chemicallybonding, either in branched or cross-linked structure, (a-1) anethylene-unsaturated alkyl carboxylate copolymer or (a-2) anolefin-based copolymer composed of an α-olefin and a glycidyl ester ofan α, β-unsaturated acid with one or more of (b) a polymer or copolymermainly comprising a repeating unit represented by the following generalformula (1):

(wherein, R represents hydrogen or a lower alkyl group, X represents oneor more groups selected from —COOH, —COOCH₃, —COOC₂H₅, —COOC₄H₉,—COOCH₂CH(C₂H₅)C₄H₉,

and —CN.)

Such graft copolymer particularly has an effect for improving heat shockproperty, and is particularly suitable as the impact resistance givingagent. Specific examples of the ethylene-unsaturated alkyl carboxylatecopolymer (a-1) include random copolymers such as an ethylene-acrylicacid copolymer, ethylene-methacrylic acid copolymer, ethylene-acrylicacid-ethyl acrylate copolymer, ethylene-ethyl acrylate copolymer,ethylene-vinyl acetate copolymer and ethylene-vinyl acetate-ethylacrylate copolymer, and further, these copolymer can also be mixed foruse. As α-olefin which is one monomer constituting the olefin-basedcopolymer (a-2), ethylene, propylene and butene-1 are listed, andethylene is preferably used. The glycidyl ester of an α, β-unsaturatedacid which is another monomer constituting the component (a-2) is acompound represented by the following general formula (2) and examplesthereof include glycidyl acrylate, glycidyl methacrylate and glycidylethacrylate, and particularly glycidyl methacrylate is preferably used.

(wherein, R¹ represents hydrogen or a lower alkyl group.)

An α-olefin (for example, ethylene) and a glycidyl ester of an α,β-unsaturated acid can be copolymerized usually by a well-known radicalpolymerization reaction to obtain a copolymer (a-2). The segment (a-2)is suitably constituted of 70 to 99% by weight of α-olefin and 30 to 1%by weight of a glycidyl ester of an α, β-unsaturated acid.

Then, the polymer or copolymer (b) to be graft-polymerized with theolefin-based copolymer (a-1) or (a-2) is a homopolymer constituted ofone of the repeating unit represented by the general formula (1) or acopolymer constituted of two or more repeating units represented by thegeneral formula (1). Examples thereof include polymethyl methacrylate,polyethyl acrylate, polybutyl acrylate, poly2-ethylhexyl acrylate,polystyrene, polyacrylonitrile, acrylonitrile-styrene copolymer, butylacrylate-methyl methacrylate copolymer and butyl acrylate-styrenecopolymer, and a butyl acrylate-methyl methacrylate copolymer isparticularly preferable. These polymers or copolymers (b) are alsoprepared by radical polymerization of corresponding vinyl-basedmonomers.

The graft copolymer used in the present invention has its feature thatthe above-described olefin-based copolymer (a-1) or (a-2) or the(co)polymer (b) is not used alone but it is a graft copolymer having abranched or cross-linked structure in which the copolymer (a-1) or (a-2)is chemically bonded with the (co)polymer (b) at least via one point,and, by forming a graft structure, a remarkable effect can be obtainedas describe later which is not obtained simply by compounding thecomponent (a-1), (a-2) or (b) alone. Here, it is suitable that the ratioof the component (a-1) or (a-2) to (b) for constituting a graftcopolymer is from 95:5 to 5:95 (by weight), preferably from 80:20 to20:80.

The production of the graft copolymer used in the present invention maybe conducted by any generally well-known method such as a chain transfermethod and an ionizing radiation irradiating method. However, mostpreferable is a grafting reaction of polymers each other, in which agrafted precursor, prepared by copolymerizing a monomer of the component(b) with a radical (co)polymerizable organic peroxide is melt kneaded ina main chain component particle. The reason for this is that graftingefficiency is high and secondary coagulation by heat does not occur,leading more effective manifestation of abilities.

As the styrene-based elastomer, block copolymers composed of a polymerblock mainly comprising a vinyl aromatic compound such as styrene and apolymer block mainly comprising a conjugated diene compound nothydrogenated and/or hydrogenated are listed. The vinyl aromatic compoundconstituting such block copolymer is at least one member selected fromthe group consisting of styrene, α-methylstyrene, vinyltoluene, p-tertbutylstyrene, divinylenzene, p-methylstyrene and 1,1-diphenylstyrene,and among them, styrene is preferable. The conjugated diene compound isat least one member selected from the group consisting of butadiene,isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, pyrelyrene,3-butyl-1,3-octadiene, phenyl-1,3-butadiene, and among them, butadiene,isoprene and combinations thereof are preferable. The block copolymerherein referred to is a block copolymer composed of a polymer block Amainly comprising a vinyl aromatic compound and a polymer block B mainlycomprising a conjugated diene compound, and the copolymerization ratioof the vinyl aromatic compound to the conjugated diene compound is from5/95 to 70/30, particularly preferably from 10/90 to 60/40.

The number-average molecular weight of the block copolymer used in thepresent invention is in the range from 5000 to 600000, preferably from10000 to 500000, and the molecular weight distribution [ratio ofweight-average molecular weight (Mw) to number-average molecular weight(Mn)] is 10 or less. The molecular structure of the block copolymer maybe any of linear, branched, radial, or combinations thereof. Examplesthereof include vinyl aromatic compound-conjugated diene compound blockcopolymers having a structure such as A-B-A, B-A-B-A, (A-B-)₄Si andA-B-A-B-A. Further, the unsaturated bond of the conjugated dienecompound of the block copolymer may be partially hydrogenated.

As the method for producing the block copolymer used in the presentinvention, any can be adopted providing a copolymer having theabove-described structure is obtained. For example, according to methodsdescribed in JP-B Nos. 40-23798, 43-17979 and 56-28925, vinyl aromaticcompound-conjugated diene compound block copolymers can be synthesizedin an inert solvent using a lithium catalyst and the like. Further,according to methods described in JP-B Nos. 42-8704, 43-6636 and59-133203, hydrogenation can be conducted in the presence of ahydrogenation catalyst in an inert solvent to obtain partiallyhydrogenated block copolymers to be used in the present invention.

The above-described block copolymer can be epoxidized to obtain anepoxy-modified block copolymer usable in the present invention. Theepoxy-modified block copolymer in the present invention can be obtainedby reacting the above-described block copolymer with an epoxydizingagent such as hydroperoxides and peracids, in an inert solvent. Thehydroperoxides include hydrogen peroxide, tertiary butyl hydroperoxideand cumene peroxide. The peracids include performic acid, peraceticacid, perbenzoic acid and pertrifluoroacetic acid. Among them, peraceticacid is a preferable epoxidizing agent because it is producedindustrially in large amount, available cheaply, and highly stable.

A catalyst can be used if necessary in the epoxidation. For example, inthe case of a peracid, an alkali such as sodium carbonate and an acidsuch as sulfuric acid can be used as the catalyst. Further, in the caseof hydroperoxides, a mixture of tungstic acid with sodium hydroxide canbe used together with hydrogen peroxide, or molybdenum hexacarbonyl canbe used together with tertiary butyl hydroperoxide to obtain catalyticeffect. The amount of the epoxidizing agent is not regulated strictly,and the optimum amount in each case is determined by a variable factorsuch as each epoxidizing agent used, degree of epoxidation desired andeach block copolymer used.

The inert solvent can be used for the purpose of reducing the viscosityof a raw material, stabilizing an epoxidizing agent by dilution, and thelike. In the case of a peracetic acid, aromatic compounds such as ethersand esters can be used. Particularly preferable solvents are hexane,cyclohexane, toluene, benzene, ethyl acetate, carbon tetrachloride andchloroform. The epoxidation reaction condition is not strictlyregulated. The reaction temperature range which can be used isdetermined by the reactivity of an epoxidizing agent used. For example,in the case of a peracetic acid, the reaction temperature is preferablyfrom 0 to 70° C. At 0° C. or lower, the reaction is slow, and at 70° C.or higher, decomposition of the peracetic acid occurs. In the tertiarybutyl hydroperoxide/molybdenum dioxide diacetyl acetate system which isone example of hydroperoxide, a preferable temperature range is from 20to 150° C. due to the same reason. Specific treatment of the reactionmixture is not required, and for example, the mixture may advantageouslybe stirred for 2 to 10 hours. Isolation of the resulted epoxy-modifiedcopolymer can be conducted by a suitable method, for example, a methodin which precipitation is effected from a poor solvent, a method inwhich a polymer is put into hot water with stirring and the solvent isremoved by distillation and a method in which a solvent is removeddirectly.

The epoxy equivalent of the above-described epoxy-modified blockcopolymer is preferably from 140 to 2700 g/mol, and particularlypreferably from 200 to 2000 g/mol. When the epoxy equivalent is over2700 g/mol, compatibility is not sufficient, and phase separation tendsto occur. On the other hand, when less than 140 g/mol, particularly aside reaction of a gelled substance and the like tends to occur inisolation of a polymer, undesirably.

Examples of the polyester-based elastomer include, but are not limitedto, block copolymers comprising a hard segment composed of an aromaticpolyester such as polyethylene terephthalate and polybutyleneterephthalate, and a soft segment composed of a polyether such aspolyethylene glycol and polytetramethylene glycol or of an aliphaticpolyester such as polyethylene adipate, polybutylene adipate andpolycaprolactone.

Examples of the polyamide-based elastomer include, but are not limitedto, block copolymers composed of a hard segment comprising nylon 6,nylon 66, nylon 11 or nylon 12 and a soft segment comprising a polyetheror an aliphatic polyester.

Examples of the urethane-based elastomer include, but are not limitedto, block copolymers comprising a hard segment composed of apolyurethane obtained by reacting a diisocyanate such as4,4′-diphenylmethane diisocyanate, 4,4′-dicyclohexylmethanediisocyanate, tolylene diisocyanate and hexamethylene diisocyanate witha glycol such as ethylene glycol and tetramethylene glycol, and a softsegment composed of a polyether such as polyethylene glycol,polypropylene glycol and polytetramethylene glycol or of an aliphaticpolyester such as polyethylene adipate, polybutylene adipate andpolycaprolactone.

On the other hand, the core shell polymer is a core shell type graftcopolymer having a multi-layer structure and preferably in which arubber layer having an average particle size of 1.0 μm or less iswrapped with a vitreous resin. The rubber layer of the core shell typecopolymer has an average particle size of 1.0 μm or less, and preferablerange is from 0.2 to 0.6 μm. If the average particle size of the rubberlayer is over 1.0 μm, the effect for improving impact resistanceproperty may be insufficient. As the rubber layer of this core shelltype copolymer, those obtained by copolymerization/graftcopolymerization of a silicon-based, diene-based or acrylic elastomersingly or two or more elastomer components selected from them can beused.

The silicon-based elastomer is produced by polymerizing anorganosiloxane monomer, and examples of the organosiloxane used includehexamethyltricyclosiloxane, octamethylcyclosiloxane,decamethylpentacyclosioxane, decamethylhexacyclosiloxane,trimethyltriphenylsiloxane, tetramethylphenylcyclotetrasiloxane andoctaphenylcyclotetrasiloxane. The acrylic rubber is obtained bypolymerizing an acrylate such as butyl acrylate and a small amount ofcross-linkable monomer such as butylene diacrylate.

As the above-described acrylate, methyl acrylate, ethyl acrylate, propylacrylate, hexyl acrylate and 2-ethylhexyl acrylate are listed, inaddition to butyl acrylate. As the cross-linkable monomer, esters ofpolyol and acrylic acid such as butylene dimethacrylate andtrimethylolpropane, in addition to butylene diacrylate, vinyl compoundssuch as divinylbenzene, vinyl acrylate and vinyl methacrylate, and allylcompounds such as allyl acrylate, allyl methacrylate, diallyl malate,diallyl fumarate, diallyl itanylate, monoallyl malate, monoallylfumarate and triallyl cyanurate. An example of the diene-based rubberincludes a polybutadiene obtained by polymerizing a butadiene monomer.

For the shell layer formed with a vitreous resin of the core shell typecopolymer, a vinyl-based copolymer is used. The vinyl-based polymer isobtained by polymerizing or copolymerizing at least one monomer selectedfrom the group aromatic vinyl monomers, vinyl cyanide monomer,methacrylate monomers and acrylate monomers. The rubber and shell layersof such a core shell type copolymer are usually bonded by graftcopolymerization. This graft copolymerization is accomplished by, ifnecessary, adding a graft crossing agent, which reacts with the shelllayer in polymerizing the rubber layer, to impart a reactive group tothe rubber layer, then, by forming the shell layer. As the graftcrossing agent, in the case of the silicone-based rubber, anorganosiloxane having a vinyl bond or an organosiloxane having a thiolis used. Preferably, acryloxysiloxane, methacryloxysiloxane andvinylsiloxane are used.

Examples of the core shell polymer as described above include Kane AceFM manufactured by Kaneka Corp., Metabrene W-300, W-530, S-2001manufactured by Mitsubishi Rayon Co., Ltd., Acryloid KM-323, KM-330manufactured by Rohm & Haars, Paraloid EXL-2311, -2602, -3211manufactured by Kureha Chemical Industry Co., Ltd., and StaphyloidP-3267 manufactured by Takeda Chemical Industry Ltd. (all are trademarks).

The amount compounded of the impact resistance giving agent of thecomponent (B) in the present invention is from 1 to 25% by weight in thewhole composition, and preferably from 2 to 20% by weight, furtherpreferably from 3 to 15% by weight. When the amount of the component (B)is too low, high heat shock property intended by the present inventionis not obtained, and when too high, mechanical properties such asrigidity are undesirably disturbed. The impact resistance giving agentcan be used alone or in combination of two or more.

The inorganic filler of the component (C) used in the present inventionis an essential component for the purpose of reducing the moldingshrinkage coefficient and linear expansion coefficient of a moldedarticle and improving high and low heat shock property, and variousfillers in the form of fiber or non-fiber (e.g., powder, plate) are useddepending on the object. As fibrous filler of these fillers, glassfiber, glass fiber having a non-circular cross section such as flatfiber, asbestos fiber, carbon fiber, silica fiber, silica·alumina fiber,zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber,potassium titanate fiber, and further, metal fibrous substances such asstainless, aluminum, titanium, copper and brass. Particularly, thetypical fibrous filler is glass fiber or carbon fiber. On the otherhand, as the powdery filler, carbon black, silica, quartz powder, glassbead, glass powder, calcium silicate, kaolin, talk, clay, diatomaceousearth, silicates such as wollastonite, metal oxides such as iron oxide,titanium oxide, zinc oxide and alumina, metal carbonates such as calciumcarbonate and magnesium carbonate, metal sulfates such as calciumsulfate and barium sulfate, and in addition, silicon carbide, siliconnitride, boron nitride and various metal powders are cited. As theplate-like filler, mica, glass flake and various metal foils are listed.These inorganic fillers can be used alone or in combination of two ormore. When these inorganic fillers are used, they are desirably treatedpreviously with a sizing agent or surface treatment agent, if necessary.

The amount compounded of the inorganic filler (C) in the presentinvention is from 1 to 50% by weight in the whole composition, andpreferably from 10 to 45% by weight, further preferably from 20 to 40%by weight. When the amount is too low, the effect for improving heatshock resistance is low, and when too high, molding work becomesdifficult.

The flame-retardant of the component (D) used in the present inventionis an essential component for securing flame-retardance of a resincomposition and an insert molded article. In the present invention,generally known flame-retardants of a resin can be used, and examplesthereof include halogen-based flame-retardants such as organic chlorinecompounds and organic bromine compounds; phosphorus-basedflame-retardants such as phosphate salts, phosphate esters,nitrogen-containing phosphorus compounds and red phosphorus; inorganicflame-retardants such as zinc borate, ammonium borate, ammoniumsulfamate, ammonium bromide; and others. Among these flame-retardants,halogen-based flame-retardants, particularly, organic bromine compoundsare suitable. Specific examples of suitable flame-retardants includebrominated aromatic bisimide compounds, brominated aromatic epoxycompounds, brominated polycarbonates, brominated benzyl acrylate andpolymerized compounds thereof and brominated polystyrene. Theflame-retardants can be used alone or in combination of two or more.

Further, for enhancing the effect of a flame-retardant if necessary,generally known flame-retardant aids can be added. For example, metaloxides and hydroxides such as antimony trioxide, antimony tetraoxide,antimony pentaoxide, sodium antimonate, tin dioxide, aluminum hydroxideand magnesium hydroxide, may be used. Particularly, when a bromine-basedflame-retardant is used, antimony compounds such as antimony trioxide,antimony tetraoxide, antimony pentaoxide and sodium antimonate aresuitable as the flame-retardant aid. The flame-retardant aid can be usedalone or in combination of two or more.

The amount compounded of the flame-retardant of the component (D) in thepresent invention is from 1 to 25% by weight in the composition, andpreferably from 5 to 20% by weight, more preferably from 10 to 20% byweight. When the amount is too small, sufficient flame-retardance cannotbe obtained, and when too large, heat shock resistance is deficient.Also, when a flame-retardant aid is used together, the total amount ofboth components is preferably in the above-described range.

Depending on use of a molded article, “V-0” of flame-retardance sectionin UL standard 94 may be required. In this case, it is preferable touse, for example, asbestos and fluorine-based resins together with aflame-retardant. The fluorine-based resin includes homo or copolymers offluorine-containing monomers such as tetrafluoroethylene,chlorotrifluoroethylene, vinylidene fluoride, hexafluoropropylene andperfluoroalkyl vinyl ether; and copolymers of the above-describedfluorine-containing monomers with copolymerizable monomers such asethylene, propylene and (meth)acrylate. Examples of such fluorine-basedresin include homopolymers such as polytetrafluoroethylene,polychlorotrifluoroethylene and polyvinylidene fluoride; and copolymerssuch as tetrafluoroethylene-hexafluopropylene copolymer,tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer,ethylene-tetrafluoroethylene copolymer andethylene-chlorotrifluoroethylene copolymer. These fluorine-based resinscan be used alone or in combination of two or more. Further, thesefluorine-based resins can be used in the form of sizing condition. Theaddition amount of the fluorine-based resin is, for example, from about0.1 to 10 parts by weight, preferably from 0.1 to 5 parts by weight,further preferably from 0.2 to 1 part by weight, to 100 parts by weightof the thermoplastic polyester resin.

The aromatic polyvalent carboxylate (E) used in the present invention isa component represented by the following general formula:

(wherein, X represents —COOR, R represents an alkyl group, n is aninteger from 2 to 4, and Rs on respective Xs may be the same ordifferent.)

Particularly when n is 3 or more, heat resistance is high, morepreferably. As the component (E), for example, trimellitate andpyromellitate are listed as preferable examples. As the alkyl groupconstituting this alkyl ester, trioctyl group, triisodecyl group,tris(2-ethylhexyl) group and tributyl group are listed, and theabove-described alkyl ester is constituted of at least one of thesealkyl groups. These aromatic polyvalent carboxylates can be used aloneor in combination.

The amount compounded of the aromatic polyvalent carboxylate (E) in thepresent invention is from 0.1 to 10% by weight in the composition, andpreferably from 0.5 to 7% by weight, particularly preferably from 1 to5% by weight. When the amount is too low, heat shock property is notsufficient, and when too high, problems occur non-preferably such asdeterioration of physical properties, e.g., rigidity, and bleeding of anaromatic ester onto the surface of a molded article.

In the present invention, other thermoplastic resin components can alsobe used accessorily in a small amount, in addition to theabove-described components, depending on the object. The otherthermoplastic resin herein used may be any resin providing it is stableat higher temperatures. For example, polyamides, polycarbonates,polyphenylene sulfide, polyphenylene oxide, polyacetal,acrylonitrile-styrene resin, acrylonitrile-butadien-styrene resin,polysulfone, polyether sulfone, polyether imide, and polyether ketone.These thermoplastic resins can also be used in combination of two ormore.

Further, in the resin composition of the present invention, there can becompounded known substances, which is generally added to thermoplasticresins and thermosetting resins, namely, stabilizers such as antioxidantand ultraviolet ray absorber, antistatic agent, coloring agents such asdye and pigments, lubricants, releasing agents and crystallizationpromoters, and crystal nucleators, for the purpose of imparting desiredproperties corresponding to the object.

The composition of the present invention is prepared easily by knownfacilities and methods generally used for preparing conventional resincompositions. Any method can be used. For example, i) a method in whichthe components are mixed, the mixture is kneaded and extruded by anextruder to prepare pellets, and then, the pellets are molded, ii) amethod in which a pellet having different composition is once prepared,the pellets are mixed in given amount and subjected to molding, toobtain a molded article having the intended composition after themolding, and iii) a method in which one or more of respective componentsare directly charged into a molding machine. Further, it is preferablethat a part of resin components is made into a fine powder, and is addedand mixed with other components, for attaining uniform compounding ofthese components.

The insert molded article referred to in the present invention is acomposite molded article obtained by charging previously a metal and thelike into a metal mold for molding, and filling the above-describedresin composition onto the outside thereof. For filling a resin in amold, there are an injection molding method, extrusion molding method,compression molding method and the like, and an injection molding methodis general. Since the material inserted into a resin is used for thepurpose of compensating defects of the resin while utilizing theproperties thereof, those which are not deformed and not melted whencome into contact with the resin are used. Therefore, those which mainlycomprises metals such as aluminum, magnesium, copper, iron, brass andalloys thereof or inorganic solids such as glass and ceramics, and whichare previously molded into bars, pins, screws and the like, are used.

Effect of the Invention

As described above, the composition of the present invention has highflame-retardance and excellent heat shock property, and an insert moldedarticle, obtained by molding this composition, can be suitably used foruses which need flame-retardance and heat shock property, for example,parts of electric and electronic products.

EXAMPLES

The following examples further illustrate the present invention indetail but do no limit the scope thereof.

The measuring methods for evaluating physical properties shown in thefollowing examples are as described below.

Oxygen Index

This was measured according to JIS K 7201. The oxygen index indicatesthe oxygen concentration necessary for continuous burning of a specimenfor 3 minutes or longer or for burning 50 mm or more of the specimen.Higher value thereof means higher flame-retardance.

Heat Shock Resistance

Pellets of a resin composition were insert-injection-molded into a moldfor specimen (a mold having a prism of length 22 mm, width 22 mm andheight 51 mm into which an iron core of length 18 mm, width 18 mm andheight 30 mm is inserted) at a cylinder temperature of 250° C., a moldtemperature of 70° C., an injection time of 20 seconds and a coolingtime of 10 seconds, so that the minimum thickness of some resin portionswas 1 mm, to produce an insert molded article (test piece). Aftermolding, the test piece was heated at 140° C. for 1.5 hours using a heatshock chamber, then, cooled down to −40° C. and kept for 1.5 hours,then, heated to 140° C. again. The heat shock test was conducted inwhich the above-mentioned heat, cool and heat steps were effected as onecycle. The numbers of the cycle until cracking occurred in 10 testpieces were measured, and the average was regarded as heat shock life,and heat shock property was evaluated. Higher value of the heat shocklife indicates higher heat shock property.

Examples 1 to 20 and Comparative Examples 1 to 11

Components (A) to (E) having compositions shown in Tables 1 to 3 weremelted and kneaded by an extruder to obtain pellets. Then, the heatshock property was evaluated as described above. The evaluation resultsare summarized in Tables 1 to 3.

The details of the components used are as shown below.

(A) Thermoplastic polyester resin

Polybutylene terephthalate (PBT); intrinsic viscosity 0.75, manufacturedby Polyplastics Co., Ltd.

(B) Impact resistance giving agent

(B1) Thermoplastic elastomer resin (E/EA-g-BA/MMA);

Graft copolymer of 70 parts by weight of ethylene-ethyl acrylatecopolymer and 30 parts by weight of methyl methacryalte-butyl acrylatecopolymer; manufactured by NOF Corp., trade name: Modiper A5300

(B2) Acrylic core shell polymer; manufactured by Kureha ChemicalIndustry Co., Ltd., trade name: Paraloid EXL-2311

(B3) Ethylene-ethyl acrylate copolymer (E/EA); manufactured by NipponUnicar Co., Ltd., trade name: Eveflex EEA A713

(B4) Methyl methacrylate-butadiene-styrene copolymer resin (MBS);manufactured by Kureha Chemical Industry Co., Ltd., trade name: ParaloidEXL-2602

(B5) Thermoplastic elastomer resin (EGMA-g-MMA);

Graft copolymer of 70 parts by weight of ethylene-glycidyl methacrylate(85:15) copolymer and 30 parts by weight of methyl methacryaltecopolymer; manufactured by NOF Corp., trade name: Modiper A4200

(B6) Epoxy-modified styrene-butadiene-styrene block copolymer (ESBS);manufactured by Daicel Chemical Industries, Ltd., trade name: EpofriendA1010

(C) Inorganic filler

(C1) Glass fiber (diameter: 10 μm)

(C2) Glass flake (thickness: about 3 μm, median particle size: about 300μm)

(D) Flame-retardant

(D1 Polypentabromobenzyl acrylate (PPBBA, manufactured by Bromokem (FarEast) Ltd., trade name: FR-1025)

(D2) Brominated Epoxy resin (BrEP, chemical name: tetrabromobisphenolA-tetrabromobisphenol A diglycidyl ether copolymer, molecular weight:about 10,000)

(D3) Antimony trioxide (Sb₂O₃) (Flame-retardant aid used together)

(E) Aromatic polyvalent carboxylate

(E1) Alkyl trimellitate; manufactured by Daihachi Chemical Industry Co.,Ltd., trade name: TOTM

(E2) Alkyl pyromellitate; manufactured by Asahi Denka Kogyo K. K., tradename: Adekasizer UL-100

TABLE 1 Example 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Composition (wt%) (A)PBT 49 47 45 47 45 42 45 47 57 47 47 47 45 42 45 45 (Ba)E/EA-g- 55 5 5 5 10 5 5 5 5 BA/MMA (B2) Core shell 5 5 5 10 5 5 polymer (B3) E/EA(B4) MBS (B5) EGMA-g-MMA (B6) ESBS (C1) Glass fiber 30 30 30 30 30 30 3030 20 30 30 30 30 30 (C2) Glass flake 30 30 (D1) PPBBA 10 10 10 10 10 1015 10 10 10 10 10 10 10 (D2) BrEP 12 12 (D3) Sb₂O₃ 5 5 5 5 5 5 5 5 5 5 55 5 5 5 (E1) Trimellitate 1 3 5 3 3 3 3 3 3 3 3 (E2) Pyromellitate 3 5 33 5 Oxygen index (%) 31 30 30 31 29 28 29 26 30 31 30 30 29 29 29 30Heat shock life (cycle) 58 100 114 123 150 80 96 180 88 90 118 130 162106 98 94

TABLE 2 Example 17 18 19 20 Composition (A) PBT 47 47 47 47 (wt %) (B1)E/EA-g-BA/MMA (B2) Core shell polymer (B3) E/EA  5 (B4) MBS  5 (B5)EGMA-g-MMA  5 (B6) ESBS  5 (C1) Glass fiber 30 30 30 30 (C2) Glass flake(D1) PPBBA 10 10 10 10 (D2) BrEP (D3) Sb₂O₃  5  5  5  5 (E1)Trimellitate (E2) Pyromellitate  3  3  3  3 Oxygen index (%) 31 27 31 29Heat shock life (cycle) 120  113  132  130 

TABLE 3 Comparative Example 1 2 3 4 5 6 7 8 9 10 11 Composition (wt %)(A)PBT 70 55 50 45 50 52 52 50 50 50 50 (B1) E/EA-g- 5 10 BA/MMA (B2)Core shell 5 polymer (B3) E/EA 5 (B4) MBS 5 (B5) EGMA-g- 5 MMA (B6) ESBS5 (C1) Glass fiber 30 30 30 30 30 30 30 30 30 30 30 (C2) Glass flake(D1) PPBBA 10 10 10 10 10 10 10 10 10 10 (D2) BrEP (D3) Sb₂O₃ 5 5 5 5 55 5 5 5 5 (E1) Trimellitate 3 (E2) Pyromellitate 3 Oxygen index (%) 1831 31 30 31 31 31 31 28 31 29 Heat shock life 40 10 37 41 40 35 43 30 2240 38 (cycle)

As apparent from examples, the compositions of the present inventionhave high flame-retardance, and excellent at shock property. If both animpact resistance giving agent and an aromatic polyvalent carboxylateare deficient, heat shock life becomes extremely short (ComparativeExample 2). If either one of an impact resistance giving agent or anaromatic polyvalent carboxylate is added, heat shock resistance issomewhat improved, but is not sufficient (Comparative Examples 3 to 11).

What is claimed is:
 1. A flame-retardant polyester resin compositioncomprising, based on the total composition weight: (A) 20-96.9% byweight of a thermoplastic polyester resin; (B) 1-25% by weight of animpact resistance agents; (C) 1-50% by weight of an inorganic filler;(D) 1-25% by weight of a flame retardant; and (E) 0.1-10% by weight ofan aromatic polyvalent carboxylate.
 2. The composition of claim 1,wherein the thermoplastic polyester resin (A) comprises polybutyleneterephthalate.
 3. The composition of claim 1, wherein the aromaticpolyvalent carboxylate (E) is at least one selected from the groupconsisting of a trimellitate and a pyromellitate.
 4. The composition ofclaim 1, wherein the impact resistance agent (B) is at least oneselected from the group consisting of thermoplastic elastomers and coreshell polymers.
 5. The composition of claim 4, wherein the thermoplasticelastomer is at least one selected from the group consisting of olefin-,styrene-, polyester-, polyamide- and urethane-based elastomers.
 6. Thecomposition of claim 1, wherein the impact resistance agent (B) is agraft copolymer in which a copolymer of ethylene with an alkylunsaturated carboxylate is chemically bonded either in a branched orcross-linking structure with one or more polymer(s) or copolymer(s)mainly comprising a repeating unit represented by the following formula(1):

(in the formula, R is hydrogen or a lower alkyl group; and X is at leastone selected from the group consisting of —COOH, —COOCH₃, —COOC₂H₅,—COOC₄H₉, —COOCH₂CH(C₂H₅)C₄H₉,

and —CN).
 7. An insert molded article comprising the composition ofclaim 1 which is insert molded with a metal or an inorganic solid.